Contrast-enhanced subtraction MR angiography in occlusive disease of the pelvic and lower limb arteries: results of a prospective intraindividual comparative study with digital subtraction angiography in 76 patients.

PURPOSE: The purpose of this work was to evaluate the feasibility and clinical use of MR angiography (MRA) for examining the pelvic and lower limb arteries in patients with arterial occlusive disease. METHOD: Seventy-six patients with clinical signs of peripheral arterial occlusive disease were included in the study. MRA was performed using a fast contrast-enhanced high-resolution 3D technique that covered the area from the distal abdominal aorta to the distal lower limbs in two examination steps. RESULTS: In all patients, diagnostic images comparable with those of conventional intraarterial digital subtraction angiography (DSA) could be obtained. No false-negative findings were seen in the iliac, femoral, or popliteal arteries. Ten to 16% of the mild stenoses and 6-14% of the severe stenoses, mainly in the crural vessels, were overgraded compared with intraarterial DSA. Particularly in patients with proximal severe obstructions or occlusions, the crural segments could be depicted more clearly due to decreased arterial runoff in conventional angiography. CONCLUSION: The consistency of the excellent depiction of the vascular territories of the distal aorta and the pelvic and lower limb arteries in a standardized setting suggests great potential for the use of MRA in the primary diagnosis of peripheral arterial occlusive disease.     

Contrast enhanced MR angiography in the assessment of relevant stenoses in occlusive disease of the pelvic and lower limb arteries: diagnostic value of a two-step examination protocol in comparison to conventional DSA.

Introduction/objectives: Contrast-enhanced MRA (ce-MRA) has been claimed by many authors as a replacement of conventional angiography evaluating peripheral arterial occlusive disease. However, reliable detection of relevant stenoses (>70%) has to be provided for planning vascular interventions. Only few data in the literature focuses on this crucial problem. The purpose of this study was to evaluate this topic using a two-step body-coil-based MRA protocol. Methods and patients: Forty three patients presenting with 82 stenoses >/=50% and 61 stenoses >70% on conventional catheter angiogram received fast Gadolinium-DTPA-enhanced high resolution 3D MR angiography at 1.5 T covering the pelvic and peripheral vascular tree in two examination steps using the body-coil. The data were evaluated double-blinded by three readers distinguishing moderate (50-70%) from severe stenoses (>70%). Results: Overall sensitivity/specificity/accuracy was 84/60/70% evaluating 143 segments. Specificity was rather poor in the iliac (58%) and crural (50%) region and moderate in the femoral and popliteal level (73%). The negative predictive value ranged between 78 and 91%. The grade of stenosis tend to be overestimated rather than underestimated in all levels with positive predictive values between 55 and 78%. Discussions and conclusions: Body-coil-based contrast-enhanced MRA has limited potential in distinguishing moderate from severe stenoses in peripheral occlusive disease. Overestimations are more common than underestimations. Both occur mainly in small-sized crural arteries but also in larger iliac arteries where vessel course in partition direction may cause inadequacy between voxel size and lumen diameter in severe stenosis.     

Diagnostic accuracy of multislice CT angiography in peripheral arterial disease

A systematic search of the PubMed and Medline databases of English literature was performed to determine the diagnostic accuracy of multislice computed tomographic (CT; MSCT) angiography in peripheral arterial disease (PAD) compared with digital subtraction angiography (DSA). Studies comparing MSCT angiography with DSA in peripheral vascular disease were included, and the diagnostic value of MSCT angiography in terms of sensitivity, specificity, and diagnostic accuracy was compared and analyzed. Ten studies (19 comparisons) met the criteria and were included for analysis. The pooled sensitivity, specificity, and accuracy rates were 92%, 91%, and 91%, respectively, at all arterial levels; 92%, 94%, and 93%, respectively, at aortoiliac arteries; 96%, 85%, and 92%, respectively, at femoropopliteal arteries; and 91%, 85%, and 87%, respectively, at infrapopliteal arteries. A significant difference was found in the sensitivity of MSCT angiography in PAD between four-slice CT and 16-slice CT, between aortoiliac and femoropopliteal arterial segments, and between femoropopliteal and infrapopliteal arterial segments (P<.05). This review demonstrates that MSCT angiography has a high diagnostic value and could be a reliable alternative to DSA in the diagnosis of PAD.     

Carotid arterial stenosis: evaluation at CT angiography with the volume-rendering technique.

PURPOSE: To determine whether computed tomographic (CT) angiography with the volume-rendering technique (VRT) can be used to accurately quantify carotid arterial stenosis and to identify occlusions. MATERIALS AND METHODS: Spiral CT was performed in 23 patients who were referred for carotid stenosis evaluation. VRT images and shaded-surface display (SSD) images of 46 carotid arterial bifurcations were compared with findings from digital subtraction angiography (DSA). RESULTS: Agreement on stenosis category between VRT CT angiography and DSA was found in 39 (85%) of the 46 carotid arteries studied. VRT CT angiography was 92% (49 of 53) sensitive and 96% (82 of 85) specific for the detection of grade 2-3 stenoses (> or = 70% stenosis). Agreement on stenosis category between SSD CT angiography and DSA was found in 38 (83%) of the 46 carotid arteries studied. SSD CT angiography was 91% (48 of 53) sensitive and 93% (79 of 85) specific for the detection of grade 2-3 stenoses. Calcified stenoses were correctly graded at VRT CT angiography in 10 of the 10 cases with heavy mural calcified plaques, while eight of the 10 stenoses were accurately quantified at SSD CT angiography. CONCLUSION: These results indicate that VRT CT angiography is as accurate as SSD CT angiography in the evaluation of carotid arterial bifurcations.     

Value of contrast-enhanced 3D MR angiography of the renal arteries

Summary Purpose: To determine the value of gadolinium-enhanced, three-dimensional breathhold Magnetic Resonance Angiography (MRA) in the assessment of the aorta and renal arteries in comparison to conventional arteriography (CA). Patients and methods: 49 patients were evaluated with both CA and 3D MRA. 0.3 mmol/kg BW gadolinium-DTPA was administered intravenously in a bolus, using an automated injector. A test bolus method was used for timing of the bolus and beginning of the data acquisition. The intraarterial CA was used as the gold standard. Results: MRA-based assessment of renal artery stenosis was identical with CA in 31 of 45 stenoses (68.8 %). Sensitivity and specificity for assessment of renal arterial disease by MRA were 84 % and 96 %; for clinically relevant lesions they amounted to 90 % and 98 %. Conclusion: The presented contrast-enhanced 3D MRA technique allows for the reliable assessment of renal arterial morphology and pathology.      

Magnetic resonance angiography in suspected cerebral vasculitis

The purpose of this study was to determine the technical capacity and diagnostic accuracy of 3D time-of-flight magnetic resonance angiography (MRA) in suspected cerebral vasculitis in a retrospective analysis of MRA and digital subtraction angiography (DSA) in 14 young patients with clinical and/or radiological suspicion of cerebral vasculitis. A total of nine arteries were evaluated in each patient. Consensus review of DSA by three observers was the reference standard. The sensitivity for detecting a stenosis varied from 62 to 79% for MRA and from 76 to 94% for DSA, depending on the observer. The specificity for detecting a stenosis varied from 83 to 87% for MRA and from 83 to 97% for DSA. Using the criterion more than two stenoses in at least two separate vascular distributions to consider the examination as being true positive, the false-positive rates for MRA and DSA were comparable. MRA plays a role as the first angiographical examination in the diagnostic work-up of suspected cerebral vasculitis. When more than two stenoses in at least two separate vascular distributions are depicted on MRA, DSA is not expected to add a significant diagnostic contribution in a patient with suspected cerebral vasculitis. DSA remains necessary when MRA is normal or when less than three stenoses are seen.     

T2 dark blood MRA for renal artery stenosis detection: preliminary observations.

OBJECTIVE: This study evaluated the ability of a fast spin echo T2 weighted dark blood sequence to characterize significant (>50%) renal artery stenosis compared to conventional angiography. METHODS: Sixteen patients underwent conventional catheter angiography for either renal artery stenosis evaluation or as potential renal donors. Each patient then had an MR study of the renal arteries and kidneys with fast spin echo T2 weighted MR (TR 4000, TE 102, 8 echo train length) on a Superconducting 1.5T Magnet. Results were compared with angiography and inter and intra observer statistics were calculated. RESULTS: A total of 36 renal arteries were imaged in 32 kidneys with 12 stenoses >50%. Fast spin echo T2 weighted MR is 94% accurate (95%CI: 87-100%) in detection of significant renal artery stenosis. Dark blood MRA (DBMRA) is 96% sensitive (95%CI: 89-100), 92% specific, with a predictive value positive of 96% for classifying real arteries as normal or significantly stenosed. Inter and intra observer statistics demonstrate good to excellent agreement in renal artery classification (kappa>0.60). CONCLUSION: DBMRA may be a useful adjunct to renal MR evaluation in hypertension. SUMMARY: A total of 36 renal arteries were imaged in 32 kidneys with 12 stenoses >50%. Fast spin echo T2 weighted MR is 94% accurate (95%CI: 87-100%) in detection of significant renal artery stenosis.     

Two-dimensional time-of-flight magnetic resonance angiography of renal arteries without maximum intensity projection: A prospective comparison with angiography in 21 patients screened for renovascular hypertension

Purpose We compared magnetic resonance angiography (MRA) with conventional angiography to establish its value as a screening test in the workup for renal hypertension.Methods Twenty one patients underwent MRA and angiography within a three day interval. Fifteen patients were suspected of having renovascular hypertension on the basis of clinical findings; the remaining six had multivessel atherosclerosis with renal insufficiency. MRA was performed on a 1 Tesla magnet in three planes: axial, coronal and perpendicular to the axis of each renal artery, by means of several contiguous or overlapping individual slice acquisitions. The two examinations were read by the same two independent observers, before and after an interval of 3 months.Results Conventional angiography showed 48 renal arteries. All main and three of six accessory renal arteries were correctly identified by MRA, as well as 11 of 14 significant stenoses or thromboses. Overreading of stenoses by MRA was observed in 4 cases. There were two false negatives for the two readers. The sensitivity and specificity of MRA for the detection of stenoses of the main renal arteries were found to be 70 and 78% respectively, for the first reading and 85 and 86% for the second reading.Conclusion MRA is considered a useful noninvasive method to determine the need for conventional angiography in patients in whom renal artery stenosis is suspected.Presented at CIRSE '92, Barcelona, Spain, 31 August 1992     

Prospective blinded evaluation of Gd-DOTA- versus Gd-BOPTA-enhanced peripheral MR angiography,as compared with digital subtraction angiography

PURPOSE: To compare the diagnostic accuracy of gadobenate dimeglumine (Gd-BOPTA)-enhanced versus gadoterate meglumine (Gd-DOTA)-enhanced magnetic resonance (MR) angiography in patients with peripheral arterial occlusive disease (PAOD). MATERIALS AND METHODS: Fifty-six patients underwent MR angiography enhanced with either Gd-DOTA (28 patients) or Gd-BOPTA (28 patients). All arterial segments from the renal arteries to the distal run-off vessels were evaluated for disease severity. The sensitivity, specificity, and accuracy of MR angiography enhanced with both agents separately were evaluated with a paired t test; digital subtraction angiography was the reference standard. Interobserver variability was assessed by using the Cohen test. RESULTS: Diagnostic MR angiograms were obtained in all 56 patients. Overall, sensitivity and specificity of Gd-DOTA-enhanced MR angiography were 96% and 93%, respectively, for observer 1 and 96% and 85%, respectively, for observer 2 (kappa = 0.82). Corresponding values for Gd-BOPTA-enhanced MR angiography were 94% and 93%, respectively, for observer 1 and 94% and 89%, respectively, for observer 2 (kappa = 0.78). No consistent differences between the two contrast materials in assessment of PAOD in the renal to popliteal arteries were observed. For assessment below the knee, specificity was slightly higher in the Gd-BOPTA group-91% and 84% for observers 1 and 2, respectively-than in the Gd-DOTA group-89% and 77%, respectively (P <.01). The number of nonassessable below-the-knee segments was significantly lower in the Gd-BOPTA group: nine of 299 segments versus 25 of 312 segments in the Gd-DOTA group (P <.01). CONCLUSION: At MR angiography of the distal run-off vessels, Gd-BOPTA yielded higher specificity and a significantly smaller number of nonassessable segments than Gd-DOTA. The diagnostic accuracy of the two gadolinium chelates at peripheral MR angiography was comparable in the renal to popliteal arteries.     

Comparison of contrast‐enhanced MR angiography to intraarterial digital subtraction angiography for evaluation of peripheral arterial occlusive disease: Results of a phase III multicenter trial

Purpose

To evaluate the efficacy and safety of 0.1 mmol/kg gadodiamide administration for contrast‐enhanced magnetic resonance angiography (CE‐MRA) in detecting hemodynamically relevant main stenosis (ie, ≥50% or occlusion) of aortoiliac arteries.

Materials and Methods

In a multicenter, phase 3, controlled study, patients with suspected or proven peripheral arterial occlusive disease (PAOD) underwent CE‐MRA with administration of gadodiamide. Intraarterial digital subtraction angiography (IA‐DSA) was used as the reference. The study was approved by all Institutional Review Boards or Institutional Ethic Committees prior to commencement of patient recruitment and written informed consent was obtained from all patients.

Results

Independent readers rated 25%–45% of CE‐MRA images as excellent compared with 0.3%–6% of noncontrast MRA images. Mean imaging acquisition time for CE‐MRA was <1 minute (0.7 ± 1.9 minutes) versus 10 minutes (10.8 ± 3.0) for noncontrast MRA. Sensitivity, specificity, and accuracy of CE‐MRA were superior compared with those of noncontrast MRA in detecting significant arterial stenoses. Compared with IA‐DSA, the sensitivity of CE‐MRA ranged from 80%–88% and the specificity from 73% to 92% for the three blinded readers, at the patient level.

Conclusion

Diagnostic results with CE‐MRA were superior and more consistent compared with noncontrast MRA for detecting hemodynamically relevant main stenoses in patients with suspected or proven PAOD and compared favorably with IA‐DSA as a reference standard. J. Magn. Reson. Imaging 2010;31:1402–1410. © 2010 Wiley‐Liss, Inc.     

Contrast-enhanced 3D FISP MR angiography of the aortic arch ostia: preliminary results

PURPOSE: The goal of this work was to evaluate three-dimensional (3D) contrast-enhanced MR angiography (MRA) for the detection of ostial stenoses of the aortic arch. METHOD: Sixteen patients with suspected carotid atherosclerotic disease prospectively underwent digital subtraction angiography of the aortic arch followed by contrast-enhanced MRA using a 3D fast imaging with steady-state precession (FISP) technique (TR = 5 ms, TE = 2 ms, flip angle = 30 degrees). Three neuroradiologists blindly measured stenoses on the catheter angiograms and MRA. Evaluation included the ostia of the innominate, left carotid, and left subclavian arteries. Any significant disagreement on catheter angiography was resolved by consensus. The MRA grades of each of the three observers were then compared with the consensus grades of the contrast angiogram. RESULTS: Forty-eight vessels were scored, of which five had significant stenoses. MRA demonstrated 100% sensitivity, 89% specificity, 52% positive predictive value, and 100% negative predictive value. The Bowker test for symmetry indicated no significant difference between conventional angiography and MRA scores (p = 0.32-0.75), and there was good agreement between the three observers (weighted kappa = 0.75-0.86). CONCLUSION: Contrast-enhanced 3D FISP MRA may be a useful imaging modality for the detection of significant stenoses at the ostia of the major aortic arch branches.     

Renal artery stenosis: Comparative evaluation of gadolinium-enhanced MRA and DSA

PURPOSE: This study was undertaken to evaluate the accuracy of contrast-enhanced magnetic resonance angiography (CE-MRA) in detecting renal artery stenosis using intra-arterial digital subtraction angiography (DSA) as the gold standard. MATERIALS AND METHODS: Thirty-five consecutive patients with possible renovascular hypertension were prospectively studied; 26 of them underwent both MRA and DSA. In these 26 cases, two readers assessed the number of renal arteries, the presence of stenoses and their degree. Results were compared with DSA, and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of MRA were determined. Interobserver variability was also calculated. RESULTS: DSA showed 51 main renal arteries (one patient had a single kidney) and six accessory arteries (total number of arteries 57) in the 26 patients considered. Both MRA readers detected all of the 51 main renal arteries and only one accessory vessel. When the presence of stenosis was considered, the readers' results, respectively, were as follows: sensitivity 77% and 72%, specificity 69% and 69%, PPV 86% and 85%, NPV 55% and 50% and diagnostic accuracy 75% and 71%. When the detection of significant stenosis was considered, the results, respectively, were: sensitivity 83% and 83%, specificity 73% and 78%, PPV 60% and 65%, NPV 90% and 91%, and diagnostic accuracy 76% and 80%. Interobserver variation was good when considering stenosis detection (kappa=0.69) and excellent when considering detection of significant stenosis (kappa=0.85). CONCLUSIONS: MRA results do not appear as positive as in the majority of papers in the literature. Multiple reasons can probably be invoked to explain this difference. The mean age of our patients, higher than in many other studies, should be noted and may have accounted for their possible poor cooperation. Moreover, all of the missed significant stenoses were distally located, and therefore, the failure to detect them might be related to the suboptimal spatial resolution of MRA. Nevertheless, MRA showed a high NPV for detecting significant stenoses, a finding of considerable clinical relevance in that it allows patients with normal MRA findings to be spared additional more invasive procedures.     

肾动脉狭窄的三维增强磁共振血管成像诊断

目的:评价高分辨力三维增强磁共振血管成像术(3DCEMRA)对肾动脉狭窄的显示准确性。方法:对30例临床诊断或怀疑肾动脉狭窄患者进行高分辨力肾动脉3DCEMRA检查,分析所有患者的肾动脉和副肾动脉显示质量和病变显示情况,并与DSA做对照。结果:3DCEMRA显示了30例患者总共59支肾动脉主干(1例为单支移植肾动脉),显示率为100%。3DCEMRA显示4支副肾动脉,显示率100%。肾动脉段级分支的显示率为49%。所有病例在动脉显示区域内静脉均未显影或显影淡,对诊断不构成影响。DSA共显示59支肾动脉主干和4支副肾动脉(以63支计算),59支主干中2支闭塞,8支重度狭窄,11支中度狭窄,10支轻度狭窄,28支肾动脉主干和4支副肾动脉都正常。3DCEMRA除把2支轻度狭窄估为中度狭窄,1支中度狭窄估为重度狭窄外,其它结果都同DSA一致,故3DCEMRA显示肾动脉主干和副肾动脉狭窄程度超过50%的有血液动力学意义的明显狭窄的敏感性和特异性分别为100%和95%,阳性预测值为91%,阴性预测值为100%。结论:高分辨力肾动脉3DCEMRA能准确检出肾动脉主干和副肾动脉狭窄,并能较好判断其狭窄程度。     

Gadobutrol-enhanced moving-table magnetic resonance angiography in patients with peripheral vascular disease: a prospective,multi-centre blinded comparison with digital subtraction angiography

The purpose of this study was to compare moving-table three-dimensional contrast-enhanced magnetic resonance angiography (CE MRA), using 1.0-mol gadobutrol, with intra-arterial digital subtraction angiography (i.a. DSA) for evaluation of pelvic and peripheral arteries in patients with peripheral arterial occlusive disease. A total of 203 patients were examined in a prospective, multi-centre study at 1.0/1.5 T. Ten vessel segments of one leg were evaluated on-site and by three independent blinded reviewers off-site. One hundred eighty-two patients were evaluable in blinded reading. For pelvis and thigh, there was statistically significant diagnostic agreement between CE MRA and i.a. DSA on-site (94%) and off-site (86-88%). Overall, for detection of clinically significant stenoses, 93% sensitivity and 90% specificity were achieved in on-site evaluation, with 71-76 and 87-93% off-site; for detection of occlusion, sensitivity and specificity on-site were 91 and 97%, with 75-82 and 94-98% off-site. Evaluation was more sensitive on-site than off-site for detection of stenoses and occlusion, whereas specificity was similar. The CE MRA with 1.0-mol gadobutrol gave results comparable to those of i.a. DSA for the larger arteries of pelvis and thigh. Results for calf arteries were compromised by spatial resolution and technical limitations.     

Comparison of contrast-enhanced ct angiography and gadolinium-enhanced MR angiography in the detection of subsegmental-sized pulmonary embolism. An experimental study in a pig model

Purpose: 
To compare contrast-enhanced CT angiography (CTA) and gadolinium-enhanced MR angiography (MRA) for the detection of subsegmental-sized pulmonary emboli in a pig model. Material and Methods: 
In 5 anesthetized pigs, 3-mm diameter embolic materials made of Konjac, a semisolid food, were introduced through the internal jugular vein into pulmonary arteries. After embolization, CTA and MRA images were obtained. Respiration was suspended during CTA and MRA image acquisition. Two readers reviewed the CTA and MRA images to detect emboli. The pigs were sacrificed, and sliced specimens of inflated lung served as the gold standard. Results: 
Thirty-six emboli were detected within peripheral arteries. The sensitivity (and 95% confidence intervals) of CTA for the two readers were 57% (39-74%) and 66% (48-81%), and 88% (69-98%) and 92% (74-94%) for MRA. The specificity of CTA was 95% (91-97%) and 98% (96-99%), and that of MRA was 85% (74-93%) and 90% (80-96%). Interobserver agreement was higher for MRA (kappa 0.898) than CTA (kappa 0.574). Conclusion: 
For the detection of subsegmental pulmonary emboli, MRA was superior to CTA, with a higher sensitivity and interobserver agreement by demonstrating perfusion deficits.     

Using gadolinium-enhanced three-dimensional MR angiography to assess arterial inflow stenosis after kidney transplantation

OBJECTIVE: Our objective was to evaluate use of gadolinium-enhanced three-dimensional (3D) MR angiography in the assessment of suspected arterial inflow stenosis after kidney transplantation. SUBJECTS AND METHODS: Twenty-eight consecutive patients receiving kidney transplants (26 single-kidney transplants and two en block transplants) with suspected arterial inflow stenosis were examined with two MR angiography sequences: gadolinium-enhanced 3D fast spoiled gradient-recalled (SPGR) imaging and 3D phase-contrast imaging. Twenty-four of these patients then were examined using the gold standards: either digital subtraction angiography (DSA) (n = 23) or surgery (n = 1). MR angiography and DSA studies were independently and prospectively analyzed for the presence of arterial stenoses (mild [<50%], severe [50-90%], or critical [>90%]) in the iliac, anastomotic, and renal artery segments. Two independent observers retrospectively evaluated the MR angiography sequences for ability to detect or exclude significant (> or = 50%) arterial stenoses. RESULTS: In 22 single-kidney transplants, DSA showed eight significant stenoses in 66 arterial segments. MR angiograms adequately showed 66 of 66 segments (prospective observers) and 64 of 66 segments (each retrospective observer), which were subsequently evaluated. The sensitivity and specificity of MR angiography in revealing significant stenoses were 100% and 98% (prospective analysis), 88% and 98% (retrospective observer 1), and 86% and 100% (retrospective observer 2). Concordance between observers showed kappa values exceeding .85 for all comparisons except the analysis of phase-contrast series (kappa = .62). In one en block transplant, DSA showed that stenosis was greater than 90%, although it had been graded at less than 50% with MR angiography. CONCLUSION: Gadolinium-enhanced 3D MR angiography accurately evaluated arterial inflow in single-kidney transplants.     

Time-of-flight magnetic resonance angiography in the follow-up of intracranial aneurysms treated with Guglielmi detachable coils

The purpose of this study was to evaluate time-of-flight magnetic resonance angiography (MRA) in the follow-up of intracranial aneurysms treated with Guglielmi detachable coils (GDCs). From January 1998 to January 2002 27 MRA and intra-arterial digital subtraction angiography (IADSA) examinations were analyzed for residual aneurysms and arterial patency following GDC placement. A total number of 33 intracranial aneurysms was analyzed, including 18 located in the posterior circulation. The MRA analysis was based on source images in combination with maximum intensity projections. The IADSA was used as the reference standard. Two aneurysms were excluded from evaluation, because of susceptibility artefacts from other aneurysms, which were clipped. Sensitivity and positive predictive values of MRA in revealing residual aneurysms were, respectively, 89% and 80%. Specificity in ruling out remnant necks and residual flow around coils was, respectively, 91% and 97%, with a negative predictive value of, respectively, 95% and 100%. Specificity and negative predictive value of MRA for arterial occlusion were, respectively, 87% and 100% for the parent arteries and, respectively, 85% and 100% for the adjacent arteries. MRA is a reliable diagnostic tool in the follow-up of GDC treatment, and it may replace IADSA in excluding residual flow around coils and aneurysmal necks and in ruling out arterial occlusion.No grant support. This paper was presented in whole at the following meetings: ECR, Vienna, March 2003; CIRSE, Lucerne, October 2002     

Prospective comparison of MRA with catheter angiography in the assessment of patients with aortoiliac occlusion before surgery or endovascular therapy

AIM: The purpose of this study was to evaluate the usefulness of gadolinium enhanced 3D magnetic resonance (MR) angiography (CE MRA) as an alternative to translumbar or brachial angiography in the pre-operative work-up of patients with aortoiliac occlusion. MATERIALS AND METHODS: Nineteen patients (14 men and five women; age range 45-77 years; mean 62 years), not suitable for perfemoral angiography (aortoiliac occlusion, n = 18; infected femoro-femoral graft with femoral artery pseudoaneurysm, n = 1), underwent pre-operative CE MRA and catheter angiography (translumbar, n = 5; brachial, n = 14). CE MRA was performed using a 3D fast spoiled gradient-recalled pulse sequence during the intravenous injection of 40 ml of gadolinium DTPA and a 32-s breath-hold. All patients subsequently underwent surgical (n = 13) or percutaneous transluminal (n = 6) treatment for their vascular disease. The accuracy of CE MRA was determined compared with the findings at catheter angiography taken as the gold standard. RESULTS: CE MRA gave accurate information about the occlusion, inflow and distal run-off in the majority of patients. CE MRA revealed occlusions with an accuracy of 94.7% in the aortic segment, 98.7% in the iliac segment, and 100% in the common femoral segment. The arterial segments distal to the common femoral artery were not completely visualized in four patients but CE MRA provided sufficient information to plan either surgical or percutaneous transluminal therapy in all but one patient. CONCLUSION: CE MRA is highly accurate in showing the presence and extent of aortoiliac occlusions. In our study group, CE MRA gave sufficient information in the pre-operative evaluation of aortoiliac occlusion.     

Magnetic resonance angiography of the carotid arteries using three different techniques: accuracy compared with intraarterial x-ray angiography and endarterectomy specimens

PURPOSE: To compare three different magnetic resonance angiography (MRA) techniques with x-ray angiography and endarterectomy specimens. MATERIALS AND METHODS: Twenty-one patients underwent x-ray angiography, three-dimensional time-of-flight (TOF) focusing on the carotid bifurcation, high-resolution (HR) contrast-enhanced (CE) MRA, and time-resolved CE MRA. Stenoses of internal carotid arteries were evaluated by three independent observers on identical projection of x-ray angiography and MRA. Maximum stenosis grades on MRA were assessed additionally and correlated with endarterectomy specimens in 12 cases. RESULTS: Sensitivity for the detection of severe stenoses was excellent (100%) for all MRA techniques, and specificity was superior for three-dimensional TOF (96.7%) compared with HR CE MRA (80.6%) and time-resolved CE MRA (83.9%). The correlation between x-ray angiography and MRA for all stenoses was slightly superior for three-dimensional TOF and HR CE MRA compared with the time-resolved technique (kappa = 0.87 and 0.86 vs. 0.84). The same trend was seen for the interobserver agreement and for the correlation with endarterectomy specimens. Eleven up to 17 stenoses (depending on the MRA technique) were graded higher using additional projections. CONCLUSION: Three-dimensional TOF MRA yielded even more accurate results than HR CE MRA in grading of stenoses near the carotid bifurcation. Therefore, a combination of both methods seems to be advantageous.     

Comparison of digital subtraction angiography with gadolinium-enhanced magnetic resonance angiography in the diagnosis of renal artery stenosis

Renal artery stenosis (RAS) is a treatable cause of hypertension and renal failure for which no ideal screening technique is currently available. We evaluated the use of dynamic gadolinium-enhanced magnetic resonance angiography (MRA) for the diagnosis of RAS. Sixty-two patients with secondary hypertension were enrolled in the study. All patients had conventional renal angiography and gadolinium enhanced MRA. The sequence used was a 3D FMP SPGR sequence with the following parameters (TR: 26 ms, TE: 6.9 ms, flip angle 40 °, field of view 36 × 36 cm, matrix 246 × 256, 1 excitation). Gadolinium 0.3 mmol/kg was administered and 60 1.5-mm-thick partitions were obtained over a duration of 3.5 min. The MRA images were then compared with conventional digital subtraction angiography (DSA) images. Conventional DSA demonstrated 138 renal arteries, whereas gadolinium-enhanced MRA demonstrated 129 (93 %). Twenty-one renal artery stenoses and four occluded arteries were seen at conventional DSA. Gadolinium-enhanced MRA had a sensitivity of 88 %, specificity of 98 %, accuracy of 96 %, positive predictive value of 92 % and negative predictive value of 97 % when compared with conventional DSA. Gadolinium-enhanced MRA is an accurate technique for identifying patients with RAS. It is less sensitive in picking up accessory renal arteries. Received: 17 March 1998; Revision received: 30 June 1998; Accepted: 28 August 1998